There has been a move in recent years in computing toward using virtualized technologies. Using virtualized technologies typically requires utilizing a hypervisor, or virtual machine monitor (VMM) operating on a host machine to run at least one virtual, or guest, machine. The hypervisor provides the guest machine's operating systems with a virtual operating platform in order to manage the execution of guest machine operating systems.
Hypervisor technology may be used by malware and rootkits which install themselves as a hypervisor below the operating system. This may render the malware or rootkit more difficult to detect because the malware could intercept operations of the operating system (such as someone entering a password) without the anti-malware software necessarily detecting it (since the malware runs below the entire operating system).